For balancing the equation, set the unit of H2SO4 as 1, then on the right side Na2SO4 has to be 1 unit to balance (SO4)2-. Then on the right side there are 2 units of Na, which makes the NaOH on the left side has to be 2 units. Now what is unbalanced is the 4H and 2O on the left side, which is equal to 2H2O on the right side.
So the final reaction equation is
H2SO4 +2NaOH → Na2SO4 +2H2O
The molar ration between Na2SO4 and NaOH is 1:2.
So when 33.3 moles of NaOH completely react with H2SO4, 33.3x1/2=16.65 moles of Na2SO4 are produced.